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Nut Handling and Processing for Confectioners and Small Nut Roasters

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Nut Handling and Processing for Confectioners and Small Nut Roasters Session 1: Microbiology of Nuts Dr. Michael Doyle, University of Georgia Sponsored by: – PowerPoint PPT presentation

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Title: Nut Handling and Processing for Confectioners and Small Nut Roasters


1
Nut Handling and Processingfor Confectioners and
Small Nut Roasters
  • Session 1 Microbiology of Nuts
  • Dr. Michael Doyle, University of Georgia

Sponsored by
In partnership with
2
Microbiology of Nuts
Microbiology of Nuts
  • Michael Doyle

3
Examples of Types of Microbes Potentially Found
on Nuts
  • Bacteria
  • Not likely harmful
  • Pseudomonas
  • E. coli
  • Xanthomonas
  • Clostridium
  • Human pathogens
  • Salmonella
  • Enterohemorrhagic E. coli (e.g., E. coli O157H7)

4
Examples of Types of Microbes Potentially Found
on Nuts
  • Molds
  • Aspergillus spp.
  • Aspergillus flavus/parasiticus - Aflatoxin
  • Penicillium spp.
  • Fusarium spp.
  • Eurotium spp.

5
Sources of Microbial Contaminants
  • Primary sources of salmonellae are intestinal
    tracts of animals (domestic and wild) and humans
    shed in feces
  • Feces can contaminate soil and water (irrigation
    and processing)
  • Salmonellae can survive in some soils for months
    to years in water for weeks to months
  • Primary sources of Enterohemorrhagic E. coli
    (e.g., E. coli O157H7) are intestinal tract of
    ruminants (e.g., cattle, goats, sheep, deer)

6
Sources of Microbial Contaminants
  • Primary source of molds such as aspergilli and
    penicillia is soil not directly related to fecal
    contamination

7
Peanuts
  • Cultivation, Harvest, Storage

8
Cultivation
  • Seed is planted in April May
  • Approximately 130 days from planting to
    harvesting
  • Cultivated in Virginia, North South Carolina,
    Georgia, Florida, Alabama, Mississippi, Texas,
    Oklahoma, and New Mexico

9
Harvesting
  • Peanuts are harvested from Aug-Nov
  • Peanuts are dug, inverted, and left in the field
    to partially dry for about 3 days before being
    combined which separates the vine from the
    inshell peanut

10
Grading/Storage
  • After the peanuts are combined, these farmer
    stock peanuts are taken to a local buying point
    for grading, drying, and storage until needed for
    shelling

11
Storage
  • Peanuts are stored in specially-designed farmers
    stock warehouses until shelled. The raw shelled
    peanuts are put in one ton tote bags and then go
    into cold storage warehouses until shipped to
    manufacturer

12
Examples of Potential Sources of Pathogen
Contamination of Peanuts During Production
  • Field fertilized with untreated manure or sewage
    as a soil amendment
  • Salmonella can survive in soil for months or
    years
  • Field irrigated with water contaminated with
    animal waste
  • Untreated surface water (ponds, rivers) with
    runoff from livestock operations
  • Wildlife grazing on or near fields

13
Examples of Potential Sources of Pathogen
Contamination of Peanuts During Storage
  • Leaks in roof on which birds congregate
  • Rodent and insect activity, especially if
    facility is near livestock operations
  • Forklift and transport equipment exposed to mud,
    water or contaminated soil outdoors brought into
    sheds and warehouses without prior cleaning and
    disinfection

14
Examples of Potential Sources of Pathogen
Contamination of Tree Nuts in Orchards
  • Cattle, livestock or wildlife grazing in orchards
    especially near trees
  • Fertilizing soil in orchards with untreated fecal
    waste
  • Shells of many tree nuts such as pecans are
    porous and can become contaminated by contact
    with soil
  • Exposure to water (rain or processing) provides
    conditions for growth of salmonellae

15
Essential Conditions for Microbial (Salmonella)
Growth
  • Food/Nutrients
  • Water/Moisture
  • Temperature

16
Characteristics of Human Pathogens That May be
Associated with Nuts
  • Salmonella
  • Can survive for months to years in low moisture
    foods such as nonfat dry milk, peanut butter,
    chocolate
  • Small numbers of this bacterium can produce
    illness when consumed in high-fat foods such as
    chocolate (lt 1 Salmonella/g), peanut butter,
    cheese

17
Characteristics of Human Pathogens That May be
Associated with Nuts
  • Salmonella (Cont)
  • Heat resistance increases with decreased moisture
    content/water activity
  • Example
  • 165F (instantaneous) kills gt 10,000,000 (gt7 log)
    Salmonella/g in ground beef, milk, poultry
  • 194F for 50 min kills 100,000 (5 log)
    Salmonella/g in peanut butter
  • 305F (oven dry heat) for 15 min kills 100,000 (5
    log) Salmonella/g on peanuts

18
Characteristics of Human Pathogens That May be
Associated with Nuts
  • Salmonella (Cont)
  • Growth prevented by low moisture content
    (water activity lt 0.95)
  • Growth typically prevented by temperature less
    than 5C (41F) or greater than 46C (115F)
  • Optimum temperature for growth is 35 - 37C (95 -
    99F)

19
Characteristics of Human Pathogens That May be
Associated with Nuts
  • Enterohemorrhagic E. coli (E. coli O157H7)
  • Can survive in soil and water for months
  • Exceptional tolerance to acidic conditions
  • Can persist in acidic foods for exceptionally
    long periods of time
  • Have a low infectious dose (lt 100 cells)
  • Cause severe symptoms in children

20
Determination of Pathogen Contamination of Nuts
and Nut Products
  • Requires a microbiological assay that has been
    specifically validated to detect the target
    pathogen (such as Salmonella) at a minimum level
    of sensitivity (e.g., 1 CFU/25 grams)
  • Methods in the FDA Bacteriological Analytical
    Manual are the gold standard for detecting
    pathogen contamination in food products regulated
    by FDA (Dec 2007 edition)
  • (http//www.foodsafety.gov/ebam/bam-5.html)

21
Determination of Pathogen Contamination of Nuts
and Nut Products
  • Methods validated to be equivalent to the FDA BAM
    protocols for detecting the target pathogen in
    specific products at the minimum level of
    sensitivity indicated by FDA, are acceptable
    alternatives

22
Determination of Salmonella Contamination of Nut
Products by FDA BAM Protocol (Cultural Method)
  • Preenrichment
  • Add 25-gm sample to 225 ml trypticase soy broth,
    mix well and incubate for 24 2 h at 35C
  • Selective enrichment
  • Incubate 0.1-ml portion of preenrichment culture
    in Rappaport-Vassiliadis (RV) medium and
    tetrathionate broth, and incubate for 24 h 2 h
    at 42C

23
Determination of Salmonella Contamination of Nut
Products by FDA BAM Protocol (Cont)
  • Selective Isolation
  • Plate onto bismuth sulfite (BS) agar, xylose
    lysine desoxycholate (XLD) agar, and Hektoen
    enteric (HE) agar, and incubate at 35C for 24
    2 h BS agar also for 48 h if no suspect colonies
    at 24 h
  • Identification/Confirmation
  • Streak suspect colonies onto MacConkey agar, HE
    agar or XLD agar, and incubate at 35C for 24 2
    h
  • Biochemical and serological assays

24
Rapid Detection of Salmonella Contamination of
Nuts and Nut Products
  • Acceptable methods for rapidly detecting (lt 8
    hrs) Salmonella in nut products should soon
    (within 2 years) be available
  • Based on shortened enrichment and molecular
    detection (e.g., Gen-Probe rRNA-based automated
    pathogen detection system) or Raman spectroscopy
    real-time (lt 5 min) assay

25
Symptoms and Consequences of Salmonellosis
  • Symptoms
  • Fever, abdominal pain, diarrhea
  • Chronic disease consequences
  • Arthritis (Reiters syndrome)
  • Onset time usually 12 - 72 hrs (can be a week)
  • Duration of illness usually resolved within 5 -
    7 days
  • Most susceptible populations generally made ill
    by lower infectious dose and experience more
    severe symptoms or death than general population

26
Symptoms and Consequences of Enterohemorrhagic E.
coli (E. coli O157H7) Infection
  • Symptoms
  • Severe abdominal cramping (like appendicitis),
    bloody diarrhea (all blood, in stools), vomiting,
    kidney failure
  • Onset time usually 3 - 4 days
  • Duration of illness usually 5 - 7 days
  • Most susceptible populations are children and
    elderly (5 - 10 of those diagnosed with EHEC
    infection) who develop renal failure (hemolytic
    uremic syndrome, HUS) which may require dialysis
    (can be permanent) and kidney transplant can
    lead to death

27
Most Susceptible Populations to Salmonella
  • Newborns, infants, the elderly and
    immunocompromised individuals are more
    susceptible to Salmonella infections than healthy
    adults
  • Incompletely developed immune system in newborns
    or infants
  • Weak or delayed immune response in the elderly
    and debilitated persons
  • Low gastric acid production in infants and seniors

28
High Fat Content of Food InfluencesInfectious
Dose
  • High fat content is common factor among foods
    associated with low infectious dose (e.g., cocoa
    butter in chocolate, milkfat in cheese and nut
    butter in nut-containing foods)
  • Suggested that entrapment of salmonellae within
    hydrophobic lipid micelles affords protection
    against the bactericidal action of gastric
    acidity
  • Rapid emptying of fat-based gastric contents
    could also provide alternate mechanism

29
Principles Used in Mitigating Risks of Pathogen
Contamination of Nuts
  • Preventing contamination throughout the entire
    cycle, from production to mouth
  • Applying control interventions from production to
    mouth
  • Moisture, temperature, vermin controls
  • Detection of pathogens and indicators of pathogen
    contamination by testing
  • Chemical antimicrobials
  • Thermal treatments
  • Non-thermal physical treatments (e.g.,
    irradiation, high pressure)
  • Responding rapidly to pathogen contamination and
    taking effective corrective action

30
  • The principles used in mitigating risks of
    pathogen
  • contamination of foods (nuts) are applied by the
    food
  • industry using a systems approach that includes
  • Sanitation Standard Operating Procedures (SSOP)
  • Current Good Manufacturing Practices (cGMP)
  • Hazard Analysis Critical Control Point Systems
    (HACCP)

31
HACCP for Nut and Nut Product Processors
  • Thermal processing is a common treatment (CCP)
    employed by the nut industry for mitigating
    pathogenic bacterial hazards

32
Theoretical Thermal Inactivation Curve for
Salmonella in Milk Chocolate at 160F (71C)
5 10 15 20
25 30
33
Thermal Inactivation of Pathogens
  • Thermal processes are designed to kill a minimum
    number of a target pathogen (e.g., Salmonella or
    E. coli O157H7)
  • Heat ground beef to internal temperature of 160F
    to kill 100,000 (5 log) E. coli O157H7/g
  • Heat canned foods to kill 12 log (12D) of
    Clostridium botulinum spores/g
  • Heat poultry to internal temperature of 165F to
    kill 5 log Salmonella/g
  • Heat almonds (peanuts) to kill at least 10,000 (4
    log) Salmonella/g

34
  • What Should Be the Targeted Log Reduction
  • for Salmonella on Nuts/Nut Products to
  • Ensure Safety?

35
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36
  • Considering the high temperature and
  • extended heating time needed to kill 5 log of
  • Salmonella in peanut butter (49 min at 194F
  • or 3.3 h at 170F), this is not likely a suitable
  • treatment to render a product of acceptable
  • quality.

37
  • Therefore, the key critical control point to
  • ensure safety from Salmonella contamination
  • from raw nuts in peanut butter/product
  • manufacture is the whole nut roaster.

38
  • If the roaster conditions are designed to kill
  • 100,000 (5 log) Salmonella/g, then the
  • incoming load of Salmonella on peanuts
  • must be less than 5 log or greater than 1
  • Salmonella will be present per gram of
  • peanuts.
  • Areas of localized Salmonella growth,
  • as occurs with A. flavus for aflatoxin
  • production, can be a confounding factor.

39
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40
Conclusions
  • Peanuts and tree nuts are now considered
    high-risk foods with regard to Salmonella
    contamination
  • The low-moisture, high-fat content of nuts
    contributes to the
  • High temperature, extended time required to kill
    Salmonella
  • Lower infectious dose of Salmonella
  • Long-term persistence of Salmonella in nut
    products

41
Conclusions
  • Mitigation of Salmonella contamination of nuts
    should be addressed from production to
    consumption.
  • Nuts should be produced and stored under
    conditions to prevent Salmonella growth.
  • The nut roaster is critical to ensuring the
    safety of nuts
  • Temperature-time conditions for nut roasting must
    be validated to ensure efficacy in killing the
    targeted number of Salmonella.
  • Roaster conditions, including nut bed depth and
    uniform loading, and accurate monitoring of
    temperatures and time, must be properly
    controlled.

42
Questions?
  • For QAs and Food Nut Safety Resource Guide
  • http//www.ecandy.com/Content.aspx?ContentID7134
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